Submitted to: Weed Technology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/21/2008
Publication Date: 1/5/2009
Citation: Anderson, R.L. 2009. Weed seedling emergence and survival as affected by crop canopy. Weed Technol. 22:736-740. Interpretive Summary: A new approach to weed management based on population dynamics has been developed. A key to success with this population-centered management is understanding seedling establishment in crops, especially crops with different growth periods. We found that seedlings of weeds prominent in corn and soybeans are not able to establish and survive in a winter wheat canopy. Winter wheat competition is lethal to the seedlings because it starts growth earlier during the growing season compared with corn or soybean. In contrast, approximately 10% of seedlings that emerged in spring wheat and canola developed into seed-bearing plants. Weeds such as common lambsquarters produced more than 1100 seeds/plant in spring wheat or canola. Weed seedlings emerged throughout the entire growing season, therefore control after harvest will be required to prevent seed production in the fall. Winter wheat may provide an opportunity to disrupt population dynamics of weeds common in corn and soybean without requiring herbicides. The population-centered approach has reduced herbicide inputs 50% in the semiarid Great Plains.
Technical Abstract: This study measured impact of cool-season crops on seedling emergence, survival, and seed production of weeds common in corn and soybean. Weed dynamics were monitored in permanently-marked quadrats in winter wheat, spring wheat, and canola. Three species, green foxtail, yellow foxtail, and common lambsquarters, comprised more than 80% of the weeds observed in the study. Seedling emergence was reduced by winter wheat but not by spring wheat or canola, when compared with adjacent quadrats without a crop canopy. Approximately 10% of seedlings in spring wheat and canola developed into seed-bearing plants, but no seed-bearing plants were present in winter wheat at harvest. Common lambsquarters produced more than 1100 seeds/plant whereas a foxtail plant produced 85 seeds, averaged across spring wheat and canola. At harvest, new seedlings were present in all crops; thus, control after harvest will be required to prevent seed production in the fall. Winter wheat may provide an opportunity to disrupt population dynamics of weeds common in corn and soybean without requiring herbicides.